Abstract

The flexsor muscle electromyogram (EMG) of the upper extremities in response to the motor cortex stimulation was inhibited by hard hand pressure on base of the ear lobe and lumbar perivertebral region and by electrical stimulation of these regions. Similar inhibition was produced by electrical stimulation around the brachium conjuctivum and locus coeruleus (BC-LC) and the reticulogigantocellular nucleus (NRGC). Inhibition of the flexor muscle EMG due to hard pressure on the body parts was abolished by electrical lesioning of the BC-LC and NRGC. The light pinch with hand on the restricted abdominal region did not inhibit the flexor muscle EMG induced by the motor cortex stimulation in normal condition, while such stimulation inhibited the flexor muscle EMG in the ulcer suffering animals after treatment with cysteamine. This inhibition was not influenced by destruction of the NRGC. From these results, it was concluded that inhibition of the motor cortex induced-flexor muscle activities caused by light pinch stimulation of the restricted abdominal region, as the model of the voluntary finger flexion inhibition in O-ring test, was produced by spinal reflex inhibition.